Author: psteitz
Date: Wed Jun 20 16:39:50 2007
New Revision: 549299
URL: http://svn.apache.org/viewvc?view=rev&rev=549299
Log:
Added log function.
JIRA: MATH-158
Modified:
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/util/MathUtils.java
jakarta/commons/proper/math/trunk/src/test/org/apache/commons/math/util/MathUtilsTest.java
jakarta/commons/proper/math/trunk/xdocs/changes.xml
Modified:
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/util/MathUtils.java
URL:
http://svn.apache.org/viewvc/jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/util/MathUtils.java?view=diff&rev=549299&r1=549298&r2=549299
==============================================================================
---
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/util/MathUtils.java
(original)
+++
jakarta/commons/proper/math/trunk/src/java/org/apache/commons/math/util/MathUtils.java
Wed Jun 20 16:39:50 2007
@@ -117,7 +117,26 @@
}
return result;
}
-
+
+ /**
+ * <p>Returns the
+ * <a href="http://mathworld.wolfram.com/Logarithm.html";>logarithm</a>
+ * for base <code>b</code> of <code>x</code>.
+ * </p>
+ * <p>Returns <code>NaN<code> if either argument is negative. If
+ * <code>base</code> is 0 and <code>x</code> is positive, 0 is returned.
+ * If <code>base</code> is positive and <code>x</code> is 0,
+ * <code>Double.NEGATIVE_INFINITY</code> is returned. If both arguments
+ * are 0, the result is <code>NaN</code>.</p>
+ *
+ * @param base the base of the logarithm, must be greater than 0
+ * @param x argument, must be greater than 0
+ * @return the value of the logarithm - the number y such that base^y = x.
+ */
+ public static double log(double base, double x) {
+ return Math.log(x)/Math.log(base);
+ }
+
/**
* Returns a <code>double</code> representation of the <a
* href="http://mathworld.wolfram.com/BinomialCoefficient.html";> Binomial
Modified:
jakarta/commons/proper/math/trunk/src/test/org/apache/commons/math/util/MathUtilsTest.java
URL:
http://svn.apache.org/viewvc/jakarta/commons/proper/math/trunk/src/test/org/apache/commons/math/util/MathUtilsTest.java?view=diff&rev=549299&r1=549298&r2=549299
==============================================================================
---
jakarta/commons/proper/math/trunk/src/test/org/apache/commons/math/util/MathUtilsTest.java
(original)
+++
jakarta/commons/proper/math/trunk/src/test/org/apache/commons/math/util/MathUtilsTest.java
Wed Jun 20 16:39:50 2007
@@ -444,6 +444,16 @@
}
}
+ public void testLog() {
+ assertEquals(2.0, MathUtils.log(2,4), 0);
+ assertEquals(3.0, MathUtils.log(2,8), 0);
+ assertTrue(Double.isNaN(MathUtils.log(-1, 1)));
+ assertTrue(Double.isNaN(MathUtils.log(1, -1)));
+ assertTrue(Double.isNaN(MathUtils.log(0, 0)));
+ assertEquals(0, MathUtils.log(0, 10), 0);
+ assertEquals(Double.NEGATIVE_INFINITY, MathUtils.log(10, 0), 0);
+ }
+
public void testGcd() {
int a = 30;
int b = 50;
Modified: jakarta/commons/proper/math/trunk/xdocs/changes.xml
URL:
http://svn.apache.org/viewvc/jakarta/commons/proper/math/trunk/xdocs/changes.xml?view=diff&rev=549299&r1=549298&r2=549299
==============================================================================
--- jakarta/commons/proper/math/trunk/xdocs/changes.xml (original)
+++ jakarta/commons/proper/math/trunk/xdocs/changes.xml Wed Jun 20 16:39:50 2007
@@ -81,6 +81,9 @@
<action dev="psteitz" type="fix" issue="MATH-166" due-to="Lukas Theussl">
Increased default precision of Gamma and Beta functions.
</action>
+ <action dev="psteitz" type="update" issue="MATH-158" due-to "Hasan
Diwan">
+ Added log function to MathUtils.
+ </action>
</release>
<release version="1.1" date="2005-12-17"
description="This is a maintenance release containing bug fixes and
enhancements.
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